This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The overall goal of our grant proposal is to evaluate the possibility that natural HIV viral env sequences that emerge during the course of HIV infection, can be used as immunogens to elicit broadly-reactive anti-HIV neutralizing antibodies. These env sequences will be derived from HIV infected subjects who during a very short period of time (2-3 years) developed broad and potent anti-HIV cross-neutralizing antibody responses. In Project 1, we will monitor HIV infected subjects to identify those that develop broad cross-neutralizing antibody responses shortly following infection and we will characterize in detail these responses. We will amplify viral env from longitudinal samples from these patients and in conjunction with Project 2 we will examine what role the CD4+ T cell helper responses have in the development and maintenance of broad anti-HIV neutralizing antibody responses and clone the neutralizing antibodies from these subjects. The Envs identified in this Project 1 will be used as immunogens in Project 3 to test the hypothesis that they can elicit broad cross-neutralizing antibody responses in animals. The Program is supported by Core A (Stamatatos) to develop protein immunogens, by Core B (L Picker and M Axthelm) to provide expertise in nonhuman primates and T cell analyses in macaques, and Core C (Haigwood) to support the entire Program with administrative support and biostatistics. We have been successful in showing that the natural genes, reconstructed as codon-optimized genes by site-directed mutagenesis (using the Robins-Kraznitz algorithm) from a subtype A patient from Kenya are highly immunogenic in rabbits, when delivered as DNA vaccines.